Question

Carbon differs from other clements of the group. Which is the falsc statement? (1) Due to its limitation of coordination number 4 (2) Due to d-orbitals in the penultimate shell. (3) Due to its unique ability to form multiple bonds. (4) Due to marked tendency to form long chains (catenation power).

Short answer

(2) Due to d-orbitals in the penultimate shell.

Step-by-step solution

- Understand Unique Properties of Carbon

Carbon is known for its ability to form a variety of bonds and structures due to its electronic configuration and bonding capabilities.

- Evaluate Coordination Number Limitation

Carbon can form a maximum of four covalent bonds due to its four valence electrons, which is a true statement.

- Analyze Presence of d-Orbitals

Carbon does not have d-orbitals in its valence shell as it only has s and p orbitals in the second (penultimate) shell. This is a false statement.

- Multiple Bond Forming Ability

Carbon can indeed form multiple bonds (double and triple bonds) with other atoms, making this a true statement.

- Tendancy to Form Long Chains

Carbon has a marked tendency to form long chains of carbon atoms, a property known as catenation, which is also a true statement.

Key concepts

Coordination Number

In chemistry, the coordination number refers to the number of atoms directly bonded to a central atom in a molecule or complex.
For carbon, the coordination number is limited to four because it has four valence electrons.
These electrons can each form a covalent bond with another atom, reaching the octet rule's stability.
This property makes carbon highly versatile in forming organic compounds, allowing for a huge diversity of molecules and structures.
Understanding coordination numbers helps in predicting molecular geometry and bonding behavior.

d-orbitals

d-orbitals play a crucial role in the bonding and properties of elements, especially transition metals.
However, carbon does not possess d-orbitals in its valence shell as it is in the second period of the periodic table.
Carbon has its electrons filling the 1s, 2s, and 2p orbitals. This constraint means it lacks the d-orbitals available for bonding.
This absence distinguishes carbon from heavier elements in the same group which might utilize d-orbitals for expanded coordination numbers or other complex bonding scenarios.

Multiple Bonds

Carbon is unique in its ability to form multiple bonds like double and triple bonds.
This happens due to the overlap of p-orbitals, allowing the formation of pi (π) bonds in addition to sigma (σ) bonds.
Multiple bonding increases the molecule's stability and affects its reactivity and properties.
For example, ethene (C2H4) contains a carbon-carbon double bond, and acetylene (C2H2) has a carbon-carbon triple bond.
Multiple bonds are crucial in organic chemistry, impacting molecule shape, reactivity, and creating the foundation for complex organic structures.

Catenation

Catenation is the ability of atoms to form long chains with themselves.
Carbon excels in catenation, forming endless chains or rings, giving rise to a vast variety of organic compounds.
This property is due to the strength of the carbon-carbon bond and the tetravalency of carbon.
Examples include straight-chain alkanes like hexane (C6H14) or aromatic rings like benzene (C6H6).
Catenation allows for the formation of complex structures from simple hydrocarbons to intricate biomolecules like DNA and proteins, demonstrating why carbon is the backbone of organic chemistry.